* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: Arial, sans-serif;
  background-color: #f4f4f4;
}

header {
  background-color: #333;
  color: white;
  text-align: center;
  padding: 1rem 0;
}

.category-nav {
  display: flex;
  justify-content: center;
  background-color: #fff;
  border-bottom: 1px solid #ddd;
}

.category-nav li {
  list-style: none;
  padding: 0.5rem 1rem;
  cursor: pointer;
  margin: 0 0.2rem;
  transition: background-color 0.3s ease;
}

.category-nav li:hover {
  background-color: #f0f0f0;
}

main {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-around;
  padding: 1rem;
}

.app-card {
  width: 200px;
  background-color: #fff;
  border: 1px solid #ddd;
  border-radius: 4px;
  padding: 1rem;
  margin: 1rem;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
  transition: transform 0.3s ease;
}

.app-card:hover {
  transform: translateY(-5px);
}

.app-card h3 {
  margin-bottom: 0.5rem;
}

.app-card p {
  color: #666;
  font-size: 0.9rem;
}
